MYP6 Unit 5 - Variation, reproduction and identity
Content
Scheme of Work
In this unit you will explore variation in living things and how living organisms reproduce. You will begin by collecting and displaying data about variation, then use this understanding to think about inheritance, identity, life cycles and human development.
The unit links data handling with biology. You will practise choosing appropriate graphs, describing correlation and using evidence to explain patterns in living things.
6u5.1 - Variation in living things
Living things are not all the same. Even individuals of the same species show differences. These differences are called variation.
Variation can be seen in animals, plants and humans. Some variation is easy to see, such as height, flower colour or fur pattern. Other variation may require measurement or careful observation.
Alive, similar, but not identical
Variation is one of the reasons why populations are interesting. A group of kittens, seedlings or students may share many features, but each individual still has its own set of characteristics.
Activity - natural variation in populations
Task
- Look at images of kittens, plants and humans.
- Identify characteristics that are shared by the whole group.
- Identify characteristics that vary between individuals.
- Sort examples into animal, plant and human variation.
Discussion
- Which differences can be described using words?
- Which differences can be measured using numbers?
- Why is variation important for survival?
Summary
- Variation means differences between individuals.
- Variation can occur in animals, plants and humans.
- Some variation is described in categories and some is measured using numbers.
Check your understanding
- Give two examples of variation in animals.
- Give two examples of variation in plants.
- Why are individuals in a population not all identical?
Teacher notes
This lesson introduces variation without yet requiring a formal genetics explanation. Use images of familiar animals and plants, plus class examples where appropriate. Avoid making students feel exposed by focusing first on non-human examples.
- LO1 - Define variation as differences between individuals.
- LO2 - Identify variation in animal, plant and human examples.
- LO3 - Distinguish between described and measured characteristics.
6u5.2 - Inherited and environmental variation
Some characteristics are inherited from parents. Other characteristics are affected by the environment. Many characteristics are influenced by both inheritance and environment.
Eye colour is mostly inherited. Language, scars, fitness and some sporting skills are strongly influenced by the environment. Height is affected by both inherited information and environmental factors such as nutrition and health.
Inherited, environmental or both?
When we describe a characteristic, we need to think carefully about what has caused it. Sometimes it is too simple to say that a characteristic is only inherited or only environmental.
Examples of influences
- Finger length - mostly inherited, but can be affected by injury.
- Eye colour - mostly inherited.
- Height - inherited and environmental.
- Ability as an athlete - inherited potential, training, diet, motivation and opportunity.
Activity - sort the characteristics
Sort a set of characteristics into three categories:
- Inherited
- Environmental
- Both inherited and environmental
For each choice, write one sentence explaining your reasoning.
Summary
- Inherited variation is passed from parents to offspring.
- Environmental variation is caused by surroundings or experiences.
- Many characteristics are caused by both inherited and environmental factors.
Check your understanding
- Is eye colour inherited, environmental or both?
- Why is athletic ability not caused by only one factor?
- Give one example of a characteristic influenced by the environment.
Teacher notes
A BBC Bitesize variation resource can be used here as a short reading or homework support. Keep explanations age-appropriate and avoid overcomplicating with dominant/recessive inheritance at this stage.
- LO1 - Classify characteristics as inherited, environmental or both.
- LO2 - Justify classifications using simple reasoning.
- LO3 - Recognise that identity is shaped by many influences.
6u5.3 - Continuous and discontinuous data
Variation can produce different types of data. Some characteristics fit into separate categories. Other characteristics can take many possible values across a range.
Discontinuous data are grouped into separate categories, such as blood group or eye colour. Continuous data are measured values, such as height, hand span or mass.
Bar graphs and histograms
A bar graph is useful for categories. A histogram is useful for continuous numerical data grouped into intervals.
Choosing a graph
- Eye colour in the class - bar graph.
- Number of siblings - bar graph.
- Height of students - histogram.
- Hand span of students - histogram.
Activity - class data collection
Task
- Collect one example of discontinuous class data.
- Collect one example of continuous class data.
- Construct an appropriate graph for each data set.
- Explain why each graph type was chosen.
Summary
- Discontinuous data are separate categories.
- Continuous data can take many values across a range.
- Bar graphs and histograms are used for different types of data.
Check your understanding
- Is height continuous or discontinuous data?
- Which graph would you use for favourite colour?
- Why is a histogram not the same as a bar graph?
Teacher notes
This lesson prepares students for the correlation work. Emphasise graph choice and axis labelling. Students may need explicit modelling of intervals for histograms.
- LO1 - Distinguish continuous and discontinuous data.
- LO2 - Select bar graphs or histograms appropriately.
- LO3 - Present class data clearly with titles, axes and units.
6u5.4 - Correlation and scatter graphs
Correlation describes a relationship between two variables. A scatter graph can show whether two measured variables are related.
A positive correlation means both variables increase together. A negative correlation means one variable increases while the other decreases. A correlation can be strong or weak depending on how closely the points follow a pattern.
Correlation does not always mean cause
A pattern on a graph can suggest a relationship, but it does not automatically prove that one variable caused the other to change. Scientists need careful evidence before making a causal explanation.
Activity - correlation investigation
Possible materials
- Shells, pinecones, leaves or other natural objects.
- Rulers or measuring tapes.
- Balance if mass is being compared.
Task
- Choose two measurable variables, such as length and width.
- Measure at least 15 objects.
- Plot a scatter graph.
- Describe the correlation as positive or negative, strong or weak.
Summary
- Scatter graphs show relationships between two measured variables.
- Correlation can be positive, negative, strong or weak.
- Correlation alone does not prove cause.
Check your understanding
- What does a positive correlation look like?
- What does a negative correlation look like?
- Why must scientists be careful when interpreting correlation?
Teacher notes & Criterion C link
This activity can be used as a formative Criterion C data-processing task. Focus on variable identification, measurement quality, scatter-graph construction and evidence-based conclusions.
- LO1 - Construct a scatter graph from paired data.
- LO2 - Describe the direction and strength of correlation.
- LO3 - Write a simple evidence-based conclusion.
6u5.5 - Sexual and asexual reproduction
Reproduction is the process by which living things produce new individuals. Different organisms reproduce in different ways.
In asexual reproduction, one parent produces offspring. In sexual reproduction, genetic information from two parents combines to produce offspring with a new combination of characteristics.
Why reproduction matters
Reproduction allows species to continue. It also helps explain why offspring often resemble their parents but are not identical to them.
Comparing reproduction
- Asexual reproduction usually produces offspring very similar to the parent.
- Sexual reproduction produces offspring with a new mixture of genetic information.
- Plants, animals, fungi and microorganisms may use different reproductive strategies.
Activity - sexual and asexual reproduction
Use short videos, diagrams and discussion to compare examples of sexual and asexual reproduction.
- Identify the parent or parents involved.
- Describe whether the offspring are likely to be identical or varied.
- Explain one advantage and one limitation of each method.
Summary
- Asexual reproduction involves one parent.
- Sexual reproduction involves combining genetic information from two parents.
- Sexual reproduction increases variation in offspring.
Check your understanding
- What is the main difference between sexual and asexual reproduction?
- Why does sexual reproduction produce variation?
- Give one example of an organism that can reproduce asexually.
Teacher notes
The Utah Learn Genetics reproduction resource can support the idea that organisms are always changing and growing up. Keep the vocabulary precise but suitable for MYP6.
- LO1 - Compare sexual and asexual reproduction.
- LO2 - Explain why sexual reproduction produces genetic variation.
- LO3 - Use reproduction vocabulary accurately.
6u5.6 - Fertilisation and reproductive strategies
Fertilisation happens when reproductive cells join and a new combination of genetic information is formed. In animals, fertilisation may happen inside the body or outside the body.
Different animals use different reproductive strategies. Some produce many offspring with little parental care. Others produce fewer offspring and invest more care in each one.
Internal and external fertilisation
Internal fertilisation happens inside the body. External fertilisation happens outside the body, often in water. Each method has advantages and limitations depending on the organism and its environment.
Activity - reproductive differences in animals
Use the handout to compare examples of animal reproduction.
- Internal or external fertilisation.
- Internal or external development.
- Number of offspring.
- Degree of parental care.
- Possible advantages of each strategy.
Summary
- Fertilisation combines genetic information.
- Animals may use internal or external fertilisation.
- Reproductive strategies vary in number of offspring and parental care.
Check your understanding
- What is fertilisation?
- What is the difference between internal and external fertilisation?
- Why might some animals produce many offspring?
Teacher notes
Use a wide range of animal examples to keep the lesson comparative rather than human-focused. This also prepares students for the animal life cycle mini-poster.
- LO1 - Define fertilisation.
- LO2 - Compare internal and external fertilisation.
- LO3 - Link reproductive strategy to survival of offspring.
6u5.7 - Animal life cycles
A life cycle shows the stages in an organism's life from reproduction to growth, maturity and reproduction again. Different animals have different life cycles.
Life cycles help us compare development, survival strategies and reproductive patterns in different organisms.
Activity - animal life cycle research
Choose one animal and research its life cycle.
Your mini-poster should include
- Name of the animal.
- Stages in the life cycle.
- Type of fertilisation and development.
- Number of offspring usually produced.
- Degree of parental care.
- At least three interesting facts.
Summary
- A life cycle shows the stages of development of an organism.
- Different animals have different patterns of growth and reproduction.
- Research can be used to compare reproductive strategies.
Check your understanding
- What is a life cycle?
- Why do some animals have larval stages?
- How can parental care affect survival?
Teacher notes
This lesson can be used for research and mini-poster production. Encourage students to avoid simply copying text. The final product should show the stages clearly and compare reproductive features using scientific vocabulary.
- LO1 - Describe the main stages of a chosen animal life cycle.
- LO2 - Use reproductive vocabulary accurately.
- LO3 - Communicate research visually and clearly.
6u5.8 - Human reproductive anatomy and puberty
The human reproductive system includes organs that produce reproductive cells, transport them and support reproduction. Puberty is the stage when hormones cause the body to mature physically and emotionally.
Hormones are chemical messengers. During adolescence they cause physical changes and can also affect mood and behaviour.
Reproductive anatomy
Students should be able to identify the main parts of the male and female reproductive systems and describe their basic functions using correct scientific vocabulary.
Activity - reproductive anatomy and functions
Task
- Label male and female reproductive anatomy diagrams.
- Match organs to their functions.
- Use student questions to clarify key ideas.
- Connect reproductive hormones to puberty changes.
Activity - reproductive cards
Sort vocabulary cards into groups and explain the reasoning for each group.
- Puberty changes
- Reproductive organs
- Hormones
- Development vocabulary
Summary
- The reproductive system contains organs with specialised functions.
- Puberty is controlled by hormones.
- Hormones can cause physical and behavioural changes during adolescence.
Check your understanding
- What is the role of reproductive cells?
- What are hormones?
- Why is puberty part of human development?
Teacher notes
Keep this section factual, respectful and classroom-safe. Establish expectations for mature scientific language. The first 25 minutes of the selected documentary clip may be used if appropriate to the school context.
- LO1 - Identify reproductive organs and their functions.
- LO2 - Explain puberty as a hormone-controlled stage of development.
- LO3 - Use reproductive vocabulary accurately and respectfully.
6u5.9 - Pregnancy, birth and development
After fertilisation, a new organism begins to develop. In humans, development takes place inside the uterus. The developing baby is supported by structures such as the placenta, umbilical cord and amniotic fluid.
Important vocabulary includes fertilisation, conception, embryo, foetus, newborn, placenta, amniotic fluid and umbilical cord.
Development before birth
The embryo is an early stage of development. Later, the developing baby is called a foetus. The placenta allows materials to be exchanged between the mother and foetus, while the umbilical cord connects the foetus to the placenta. Amniotic fluid helps protect the foetus.
Key vocabulary
- Fertilisation - joining of reproductive cells.
- Embryo - early stage after fertilisation.
- Foetus - later stage of development before birth.
- Placenta - organ for exchange of useful and waste substances.
- Umbilical cord - connection between the foetus and placenta.
- Amniotic fluid - fluid that surrounds and protects the foetus.
Activity - pregnancy and development vocabulary
Use diagrams, cards or a short documentary extract to place the stages of development in order and match each structure to its function.
Summary
- Human development begins after fertilisation.
- The embryo and foetus are stages before birth.
- The placenta, umbilical cord and amniotic fluid support development.
Check your understanding
- What is the function of the placenta?
- What does the umbilical cord connect?
- Why is amniotic fluid important?
Teacher notes
Use diagrams and careful vocabulary. The documentary Life's Greatest Miracle may be used selectively if suitable. The problem page task can be used to let students apply accurate scientific information to common questions or misconceptions.
- LO1 - Sequence key stages in human development.
- LO2 - Describe the role of placenta, umbilical cord and amniotic fluid.
- LO3 - Use development vocabulary accurately.
6u5.10 - Genetics, identity and family trees
Each person is unique. Our identity is influenced by inherited information, environment, experiences, culture, family and personal choices.
Cells contain genetic material. When cells divide, genetic information is passed on. During fertilisation, new combinations of genetic information are made.
Family trees
A family tree is a diagram that shows relationships between family members across generations. It can be used to discuss inheritance patterns in a simple visual way.
Activity - family tree construction
Create a simple family tree using symbols and connecting lines.
- Show at least three generations if possible using a fictional or example family.
- Use clear symbols and a key.
- Choose one characteristic and discuss whether it may be inherited, environmental or both.
Activity - identity discussion
Discuss the question: What makes each person unique?
- Inherited characteristics.
- Environmental influences.
- Experiences and choices.
- Culture, family and community.
Summary
- Genetic information is passed from parents to offspring.
- Fertilisation produces new combinations of genetic information.
- Identity is influenced by inheritance, environment and experience.
Check your understanding
- Why are siblings usually similar but not identical?
- What can a family tree show?
- Why is identity more than just inherited characteristics?
Teacher notes
Use fictional or teacher-provided family tree examples to avoid privacy issues. This lesson should bring the unit together by connecting variation, reproduction, inheritance and identity.
- LO1 - Describe how genetic information is passed on.
- LO2 - Construct and interpret a simple family tree.
- LO3 - Explain that identity is shaped by inherited and environmental influences.
Useful revision links
The following revision resources can be used to support the unit content.
- Animal and plant cell basics - BBC Bitesize
- Specialised animal cells - BBC Bitesize
- Specialised plant cells - BBC Bitesize
- Levels of organisation - BBC Bitesize
- Microscopes - BBC Bitesize
Some of these links also review earlier cell content from Unit 3.